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ATP turbo is releasing T3 flanged split pulse or divided non gated turbine housings for the GT30R and GT3540R (GT3582R) range of turbos . No details yet on which AR ratios they intend to do but may be useful for some . They are also selling the .85AR T4 flanged divided Garrett housing for GT40R based turbos .

Cheers Adrian .

whats involved in getting the rb25 to run split pulse? is it as simple as manifold change? or is more comlpex such as changing firing sequence of each cylinder + suitable manifold?

very good info, thanks a

OEM manifolds for the RB sixes are all split pulse (to an extent) already. the flange will be the same, they will bolt on.

personally i would never build a manifold with an open collector, even if i was using an open collector turbo. split pulse all the way. the less pressure spiking you get transmitted to the other three cylinders the better IMHO.

ok right. so its just a case the standard turbocharger doesnt run split pulse.

so it should be as simple as bolting on a split pulse turbocharger and thats all u need to do. cool cool. i was under impression you would have to change the manifold and firing sequence to suit.

split pulse works in the sense say

cylinders 1,3,4 fire

into pulse zone 1

and cylinders 2,4,6 fire

into pulse zone 2

so the engine fires in order 1,2,3,4,5,6

and this results in gas flowing through each pulse zone in well "pulses" which keeps the exhaust wheel spinning at the best possible rate

or is the goal of split pulse to avoid collision (so to speak) in the manifold

ie: no two firing cylinders at the same meet up in the same pulse zone?

the firing sequence of the RB sixes is 1 5 3 6 2 4 IIRC - you will notice that each of the three cylinders linked by a common collector are separated by the firing of a cylinder NOT linked to it.

when your back pressure spikes due to an exhaust pulse, you don't want that pressure spike being "seen" by another cylinder just as the exhaust valve is open there too, it will hinder gas exit and increase the work of pumping. so you separate them as much as you can.

ideally then, six independent pulse housings would be ideal for your turbo, but it's just not practical. even better would be six individual tiny turbos, but that would simply not work.

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